Lincoln and Hitachi make the best flux core wires ! If you get a lot of spatter your feed and heat is not correct! I have a little craftsman 110v welder and it adjusts the current to wire speed fairly well. I don't really have a spatter issue when I use Lincoln wire, the Hobart stuff is just awful oh how I hate that stuff......
Also only clean where your going to weld helps a bit too. The spatter likws to stick really good to fresh steel. Never weld down hill with flux core because the flux will out run the molten metal and pop when the metal gets on it. Always pull the the puddle so the wire looks like it is pushing the puddle back. I know this stinks because you cant always see where your going but its the best way to get the most deposition to your weld.
One trick I use is to always try and weld up hill!! This keeps the flux out and you can see what you are doing much better. On thin stuff I will weld it horizontal. And only do a little at a time.
Also welding thick metal is very hard with a little unit, but you can cheat by heating the weld area with a torch so its almost red hot!! This will allow for awesome penetrating of your weld bead and make it lay flat instead of looking like a rope played on it.

Does the flux core wire affected by dampness ? I think I got a roll with my Mig welder but never used it , can't even remember if it was in some kind of sealed package . but those that only use a roll a year does it go " bad " ?

If it gets rusty..... Its done..... Fluxcore usually has a coating on it, but some does not and as stated if its rusty its going to mess up everything, the feed rolls, liner and tip. This will cause you unbelievable greif.

As keith stated rust on the wire is bad and it is. On the other hand I by the 10 lb rolls and have never had any corrosion show up on the wire and that shop is not climate controlled. Tried different brands of wire but seem to stick with the Lincoln wire now. He also states that welding up hill is best. This is true but the angle need not be steep. Even a few degrees of incline will help a lot.

Don't be afraid to experiment with different wire speeds and heat settings.

I have a 20-year old made in US Century 110, 70amp running flux that welds cleaner and deeper than a newer Lincoln 125amp 'nascar' model which was probably made in Asia.

I had a 220 Miller running gas that was the best machine i've ever used. But no longer have 220 so had to sell. Once I got good with stick I was really impressed with what a small 220 stick welder will do with good rods. If I ever get 220 in the shop I'll get another small 220 stick welder for the big stuff and keep my little 110 wire for small stuff.

I'm glad I started to lean how to weld. The other day I went to adjust the drive chains on a Chinese dune buggy and it called for a spanner to adjust the off center drums. So I just made one using some round stock and an old piece of metal I had laying around. Worked great.

I have no experience with the 120V welders so I may not have the answer to your question. But let me tell you what I find with my welder.

I use a Miller XMT304 power source with a dual wire feeder. I do general repair and fab work for my self on farm type equipment. COWPOO does cause corrosion and ER70S-6 wire with CO/Argon with some grinding and rust removal does make a very acceptable repair. It seems to compare to 6011/6013 stick as far as welding on not new metal. Of course cleaner is always better when it comes to a quality weld.

My preference is .035 non flux core wire with a 75/25 CO/Argon mix. This seems to have less splatter than a flux core wire in my experience when the welder is set correctly.

I also advise the use of nozzle gels and anti spatter spray. These products can make you a better welder just by keeping your nozzle clean and keeping the gas flow correct. A good piece of leather is also good to have around to protect critical areas of the welding area.

Best thing is ask questions and we will do our best to get you any answer.

My first experience with flux core. See Below.

I have been helping my brother and his partner at their new hydraulic repair business and one of their welders is a large Miller power source (300 amp) with a wire feeder. They have it set up with .045 dual shield (Flux Core) with 75/25 shielding gas.

I have the worst time welding with this unit. (No practice does not help) I have a terrible time trying to see the puddle. I am using their helmet and that may be an issue. Before I give up on this welding process I am going to bring my helmet and see what it looks like.

They do most (99%) of the welding on the repaired and new manufactured cylinders with 7018 DC stick. One of my favorites.

If they are welding hydraulic cylinder barrels they should be using 100℅ argon with solid wire!! Or tig. 7018 with out a 100℅ 6013 root pass is just asking for cracks. Oh the horrors of a leaking end cap on a cylinder......

The HF 170 is a 220v outfit and can run either the flux or gas. I don't have it yet so no clue how it welds, I have only ever mig welded with a Miller Bobcat so it will be all I could compare it to. I do have an older Lincoln 225 stick machine that I have yet to use since bringing it here. As said I weld something once in 3 blue moons around here so it could sit for a year or more at a time, hence not wanting to spend 6 or 8 hundy on a big brand name. Its a gamble of sorts, long as it glues stuff together, I got a huge grinder for looks if need be.